what is a rotary engine......is it double or single engine....


Asked by Jun 03, 2009 at 05:35 PM

Question type: General

most of the time i heard that mazda RX8 or RX7 is rotary engine.......but i don't know what type of engine it is.....how it works.....is it better....

2 Answers


I would recommend using google or wikipedia to get your answer. Conventional engine design and thought really doesn't transfer well to the rotary. However, the basic principle for rotary is fairly simple. A rought triangular shape( the rotor) sits eccentrically mounted on crankshaft which it rotates around inside a chamber. The three faces of the rotor undergo the various cycles you expect from an engine (intake, compression, power, and exhaust) However they don't act linearly like they do in a piston going up and down in a cylinder bore. Instead, the rotation of the rotor is what causes the various cycles. The benefit of this is that the engine is much more compact since in effect you have three pistons sharing the same bore. This also leads to the relatively low displacement numbers for the rotaries (generally 1.3l or 2.0l). This is due to them counting the swept displacement of only one of the faces of the rotor instead of all three faces. In actuality the engine acts like a 3.9l or 6.0l, both in fuel economy and power, and really by the definition of volumetric displacement, but that's debatable. This is partly why various racing bodies will multiply the displacement when classing the vehicles. Additionally the constant rotation means a more consistent delivery of power and less vibration due to inertia of parts changing direction inside the engine. Leads to a smoother higher revving engine. Now I'm not sure what you mean by 'is it a double or a single engine', but the number of rotors varries from engine to engine. Generally speaking most have two rotors and are either 1.2l or 1.3l in displacement. However there are 3 rotor engines (typically 2.0l), and I've heard of 4 rotor motors, though I've never seen them. IMO the engine is great for a track car, but the maintenance, reliability, and fuel efficiency issues inherent in the motor make it a poor street engine Hopefully that answers some of your questions, if there is anything else you want to know just post back.


thank you very much...n' yeah it will be better if i go to google or wikipedia...

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